Nope. You are having your chain jerked.
Walnut has the edge on beech, but I have high dollar furniture made of both woods. The same goes for the stocks on the K31 - pre-44, usually walnut unless replaced by beech. Post-44 usually beech unless replaced by old stocks of walnut. The iffy-alloyed composition of SOME 1944 operating rods was due to a wartime shortage of chromium, I'd bet that most had been replaced way before you ever clapped eyes on one. In any case, IF the highly unlikely event occurs that you have such an op rod that has developed a crack in the lug that engages in the cam track of the bolt, then around $35 will get you a new one from Guisan.
tacYou choose.
tac